UNITED STATES—Suits come in two flavors: bundled and separates. Bundled suits are the most common and are available in the widest variety of colors, fabrics, styles and patterns. The suit coat and matching pants are sold as one complete purchase. Sizing for both is based on human bell curve averages. In other words, the suit size and pants size bundled together will fit most men with minimal alterations. The pants legs are always unhemmed and must be tailored for length. The only pants sizing number is waist circumference in inches.

Suit separates are where the coat and pants are sold separately. The pants are usually pre-hemmed and don’t require tailoring for leg length. Sizing has two numbers in inches: waist size and leg length. Buying separates is an option for men with body dimensions that fall outside the middle of the bell curve. Some men have athletic builds, with broad shoulders and chests, and narrow waists. Other men are portly, with wider than average waistlines. And there are men with short torsos and long legs and arms, or with long torsos and short limbs.

Suit separates make sense for such men. The disadvantage is that separates generally don’t have as wide a range of available colors, fabrics and styles compared to bundled suits. And in the past, their quality wasn’t very good. However, the overall quality of separates has now greatly improved, but there are still separates out there with less-than-desirable quality. Always pay close attention to fabric content and workmanship when purchasing any suit.

Suit coats have one principal sizing number: the chest size in inches. This can range from approximately 34 to 60 inches. Size 44 Regular is the peak of the bell curve for American males. The difference between chest size and waist size is called the drop. Standard drop is about six inches, so a size 44 coat would be bundled with a size 38 pair of pants. Athletic drop is 8 to 10 inches, and portly drop is two inches.

For suit coats, there are letter codes that provide additional sizing information: R, S, L, A, P, and X. R is regular, and refers to the overall length of the coat, which should end at the thumb tip with the arms relaxed at the sides. S stands for short, and is a coat length for men with shorter torsos and arms than R. L means long, for longer coats designed for tall, lanky individuals.

A is for athletic fit, for muscular men with broad shoulders and small waists. P stands for portly. X means extra, and can be doubled or tripled as needed. These letter codes can be combined. For example, a suit size of 58XXLXP translates to a suit coat with a 58-inch chest, an extra, extra long length and designed with an extra portly drop (the pants waist might be 58 inches).

Keep in mind that sizing numbers (and letters) are approximations, and can vary considerably from garment to garment. They are only a general guide to fit. Always try on clothes before buying. Your body will never lie to you about fit.